package com.xzll.common.util;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.Date;
import java.util.List;
import java.util.concurrent.*;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * @Author: hzz
 * @Date: 2023/3/6 17:08:33
 * @Description: 线程池监控工具
 */
public class ThreadMonitorUtil extends ThreadPoolExecutor {

	private static final Logger LOGGER = LoggerFactory.getLogger(ThreadMonitorUtil.class);

	// 保存任务开始执行的时间，当任务结束时，用任务结束时间减去开始时间计算任务执行时间
	private ConcurrentHashMap<String, Date> startTimes;

	// 线程池名称，一般以业务名称命名，方便区分
	private String poolName;

	/**
	 * 调用父类的构造方法，并初始化HashMap和线程池名称
	 *
	 * @param corePoolSize
	 *            线程池核心线程数
	 * @param maximumPoolSize
	 *            线程池最大线程数
	 * @param keepAliveTime
	 *            线程的最大空闲时间
	 * @param unit
	 *            空闲时间的单位
	 * @param workQueue
	 *            保存被提交任务的队列
	 * @param poolName
	 *            线程池名称
	 */
	public ThreadMonitorUtil(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> workQueue,
						 String poolName) {
		super(corePoolSize, maximumPoolSize, keepAliveTime, unit, workQueue, new EventThreadFactory(poolName));
		this.startTimes = new ConcurrentHashMap<>();
		this.poolName = poolName;
	}

	/**
	 * 线程池延迟关闭时（等待线程池里的任务都执行完毕），统计线程池情况
	 */
	@Override
	public void shutdown() {
		// 统计已执行任务、正在执行任务、未执行任务数量
		LOGGER.info(String.format(this.poolName + " Going to shutdown. Executed tasks: %d, Running tasks: %d, Pending tasks: %d",
				this.getCompletedTaskCount(), this.getActiveCount(), this.getQueue().size()));
		super.shutdown();
	}

	/**
	 * 线程池立即关闭时，统计线程池情况
	 */
	@Override
	public List<Runnable> shutdownNow() {
		// 统计已执行任务、正在执行任务、未执行任务数量
		LOGGER.info(
				String.format(this.poolName + " Going to immediately shutdown. Executed tasks: %d, Running tasks: %d, Pending tasks: %d",
						this.getCompletedTaskCount(), this.getActiveCount(), this.getQueue().size()));
		return super.shutdownNow();
	}

	/**
	 * 任务执行之前，记录任务开始时间
	 */
	@Override
	protected void beforeExecute(Thread t, Runnable r) {
		startTimes.put(String.valueOf(r.hashCode()), new Date());
	}

	/**
	 * 任务执行之后，计算任务结束时间
	 */
	@Override
	protected void afterExecute(Runnable r, Throwable t) {
		Date startDate = startTimes.remove(String.valueOf(r.hashCode()));
		Date finishDate = new Date();
		long diff = finishDate.getTime() - startDate.getTime();
		// 统计任务耗时、初始线程数、核心线程数、正在执行的任务数量、已完成任务数量、任务总数、队列里缓存的任务数量、池中存在的最大线程数、最大允许的线程数、线程空闲时间、线程池是否关闭、线程池是否终止
		LOGGER.info(String.format(this.poolName
						+ "-pool-monitor: Duration: %d ms, PoolSize: %d, CorePoolSize: %d, Active: %d, Completed: %d, Task: %d, Queue: %d, LargestPoolSize: %d, MaximumPoolSize: %d,  KeepAliveTime: %d, isShutdown: %s, isTerminated: %s",
				diff, this.getPoolSize(), this.getCorePoolSize(), this.getActiveCount(), this.getCompletedTaskCount(), this.getTaskCount(),
				this.getQueue().size(), this.getLargestPoolSize(), this.getMaximumPoolSize(), this.getKeepAliveTime(TimeUnit.MILLISECONDS),
				this.isShutdown(), this.isTerminated()));
	}

	/**
	 * 创建固定线程池，代码源于Executors.newFixedThreadPool方法，这里增加了poolName
	 *
	 * @param nThreads
	 *            线程数量
	 * @param poolName
	 *            线程池名称
	 * @return ExecutorService对象
	 */
	public static ExecutorService newFixedThreadPool(int nThreads, String poolName) {
		return new ThreadMonitorUtil(nThreads, nThreads, 0L, TimeUnit.MILLISECONDS, new LinkedBlockingQueue<Runnable>(), poolName);
	}

	/**
	 * 创建缓存型线程池，代码源于Executors.newCachedThreadPool方法，这里增加了poolName
	 *
	 * @param poolName
	 *            线程池名称
	 * @return ExecutorService对象
	 */
	public static ExecutorService newCachedThreadPool(String poolName) {
		return new ThreadMonitorUtil(0, Integer.MAX_VALUE, 60L, TimeUnit.SECONDS, new SynchronousQueue<Runnable>(), poolName);
	}

	/**
	 * 生成线程池所用的线程，只是改写了线程池默认的线程工厂，传入线程池名称，便于问题追踪
	 */
	static class EventThreadFactory implements ThreadFactory {
		private static final AtomicInteger poolNumber = new AtomicInteger(1);
		private final ThreadGroup group;
		private final AtomicInteger threadNumber = new AtomicInteger(1);
		private final String namePrefix;

		/**
		 * 初始化线程工厂
		 *
		 * @param poolName
		 *            线程池名称
		 */
		EventThreadFactory(String poolName) {
			SecurityManager s = System.getSecurityManager();
			group = (s != null) ? s.getThreadGroup() : Thread.currentThread().getThreadGroup();
			namePrefix = poolName + "-pool-" + poolNumber.getAndIncrement() + "-thread-";
		}

		@Override
		public Thread newThread(Runnable r) {
			Thread t = new Thread(group, r, namePrefix + threadNumber.getAndIncrement(), 0);
			if (t.isDaemon())
				t.setDaemon(false);
			if (t.getPriority() != Thread.NORM_PRIORITY)
				t.setPriority(Thread.NORM_PRIORITY);
			return t;
		}
	}


}
